Environmental stress sensitivity of an ascorbic acid-deficient Arabidopsis mutant
Environmental stress sensitivity of an ascorbic acid-deficient Arabidopsis mutant
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DOI：
10.1073/pnas.93.18.9970
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发表时间：
1996-09-03
影响因子：
11.1
通讯作者：
Last, RL
中科院分区：
文献类型：
--
作者：
Conklin, PL;Williams, EH;Last, RL
L-抗坏血酸(维生素C)是一种在植物中发现的毫米级浓度的强大还原剂，被认为在清除植物和动物的自由基方面发挥着重要作用。然而，令人惊讶的是，人们对这种抗氧化剂在植物环境胁迫适应或抗坏血酸生物合成中的作用知之甚少。我们报道了SOZ1的分离，这是一种半显性臭氧敏感突变体，仅积累正常抗坏血酸浓度的30%。遗传途径和取食研究的结果表明，抗坏血酸浓度影响叶片对臭氧氧化气体的抗性。与所提出的抗坏血酸在活性氧物种解毒中的作用一致，臭氧熏蒸后SOZ1中的过氧化脂质升高，但在野生型中没有。我们发现，soz1突变体对二氧化硫和紫外线B辐射都高度敏感，因此抗坏血酸对不同的环境胁迫具有防御作用。除了确定植物中第一个缺乏抗坏血酸的突变体外，这些结果表明筛选臭氧敏感突变体是鉴定重要的生理抗氧化机制和信号转导途径的有效方法。对SOZ1的分析应该会带来更多关于抗坏血酸的生理作用和代谢的信息。
L-ascorbic acid (vitamin C) is a powerful reducing agent found in millimolar concentrations in plants, and is proposed to play an important role in scavenging free radicals in plants and animals. However, surprisingly little is known about the role of this antioxidant in plant environmental stress adaptation or ascorbate biosynthesis. We report the isolation of soz1, a semi-dominant ozone-sensitive mutant that accumulates only 30% of the normal ascorbate concentration. The results of genetic approaches and feeding studies show that the ascorbate concentration affects foliar resistance to the oxidizing gas ozone. Consistent with the proposed role for ascorbate in reactive oxygen species detoxification, lipid peroxides are elevated in soz1, but not in wild type following ozone fumigation. We show that the soz1 mutant is hypersensitive to both sulfur dioxide and ultraviolet B irradiation, thus implicating ascorbate in defense against varied environmental stresses. In addition to defining the first ascorbate deficient mutant in plants, these results indicate that screening for ozone-sensitive mutants is a powerful method for identifying physiologically important antioxidant mechanisms and signal transduction pathways. Analysis of soz1 should lead to more information about the physiological roles and metabolism of ascorbate.